Internal gear-wheel pump comprising reinforced channels

ABSTRACT

The invention relates to a gerotor fuel pump ( 2 ) comprising ribs ( 18, 19 ), which are located in channels ( 16, 17 ) that are configured as inlets and outlets and that are situated in housing parts ( 8, 9 ). The ribs ( 18, 19 ) are positioned transversely to the maximal extension of the cross-sections of the channels ( 16, 17 ), producing a high degree of stability in the channels ( 16, 17 ). The housing parts ( 8, 9 ) are composed of plastic.

BACKGROUND OF THE INVENTION

The invention relates to a gerotor fuel pump for feeding fuel from a fuel tank of a motor vehicle having a housing, having a rotor pair mounted between two housing parts, and having elongated inlet and outlet ducts arranged in the housing.

Fuel pumps of this type are often used in particular to feed diesel fuel in modern-day motor vehicles, and are known from practice. The rotor pair of the gerotor fuel pump has an inner rotor with external toothing and an outer rotor with internal toothing. Here, the external toothing usually has one tooth more than the internal toothing. The rotational centre of the inner rotor is offset with respect to the rotational centre of the outer rotor. The inlet and outlet ducts are usually arranged in opposing housing parts. As a result, flow passes axially through the fuel pump.

A disadvantage of the known fuel pump is that the elongated inlet and outlet ducts adversely affect the stability of the housing. In practice, this can be dealt with by arranging in the housing parts a steel reinforcing ring for radially fixing, and two ceramic plates or metal plates for axially delimiting, the rotor pair. The known fuel pump is very costly as a result.

The object on which the invention is based is that of developing a fuel pump of the type mentioned in the introduction in such a way that it is of particularly simple construction and can be produced cost-effectively.

BRIEF DESCRIPTION OF THE INVENTION

This problem is achieved according to the invention in that at least one of the ducts has at least one rib for strengthening the housing.

With this embodiment, the rib can reinforce the duct and thus prevent the housing from bending in the region of the duct. As a result, the housing has a particularly high stability in the region of the duct. High stability is particularly advantageous at the outlet since high forces act on that region of the housing which has the outlet duct. As a result, bending of the housing in the region of the ducts which is caused by the occurring forces can be eliminated. The housing can be produced from a very thin-walled and cost-effective material as a result. In this way, the fuel pump according to the invention requires no separate reinforcing rings to be mounted, is therefore of particularly simple construction and can additionally be produced particularly cost-effectively.

A plurality of ribs could, for example, cover the ducts in the manner of a grid. According to another advantageous embodiment of the invention, the number of ribs can be kept particularly low if the at least one rib is arranged transversely with respect to the longest extent of the duct cross section, and connects opposing edges of the housing, which delimit the duct, to one another. In addition, the dimensions and thus a throttling effect of the ribs are kept particularly low as a result.

The outlay in terms of assembly of the fuel pump according to the invention can be reduced further if the rib is produced in one piece with those regions of the housing which adjoin the ducts.

The fuel pump according to the invention can be produced particularly cost-effectively if at least one of the housing parts is produced from plastic. The low strength of the plastic housing parts in comparison to the ceramic plates of the known fuel pump is compensated for by the ribs in the ducts.

According to another advantageous refinement of the invention, the housing parts can be connected with a particularly low structural outlay if the housing parts are screwed to one another, one of the plastic housing parts having receptacles for metal nuts. The metal nuts ensure sufficient stability of the fuel pump according to the invention.

DESCRIPTION OF THE DRAWINGS

The invention permits a large number of embodiments. In order to further clarify its basic principle, one embodiment is illustrated in the drawing and is described in the following. In the drawings:

FIG. 1 shows a section illustration through a feed unit having a fuel pump according to the invention;

FIG. 2 shows an exploded illustration of the fuel pump according to the invention in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a section illustration through a feed unit for feeding diesel fuel from a fuel tank (not illustrated) of a motor vehicle to an internal combustion engine having a fuel pump 2 which is driven by an electric motor 1. The fuel pump 2 has an inner rotor 4 which is connected to a shaft 3 of the electric motor 1 and forms a rotor pair 6 with an outer rotor 5. The outer rotor 5 is mounted radially in an annular element 7 and axially between two housing parts 8, 9 of a housing 10. A coupling 11 is arranged on the shaft 3 of the electric motor 1 and is connected in a rotationally fixed manner to the inner rotor 4. In addition, the shaft 3 has a radial bearing with a bush 12 in that housing part 8 of the fuel pump 2 which faces away from the electric motor 1. A pump cover 13 has an intake pipe 14. On its end facing away from the fuel pump 2, the feed unit has a connecting pipe 15 for a fuel line which leads to the internal combustion engine. As a result, the supplied fuel flows axially through the feed unit.

In an exploded illustration of the fuel pump 2 from FIG. 1, FIG. 2 shows that the housing parts 8, 9 each have an elongated duct 16, 17. The duct 17 arranged in the housing part 9, which is intended to be arranged near the electric motor 1 from FIG. 1, serves as an outlet of the fuel pump 2, while the duct 16 arranged in the housing part 8, which is intended to be arranged near the pump cover 13 from FIG. 1, forms an inlet of the fuel pump 2. The housing parts 8, 9 each have ribs 18, 19 respectively which are arranged transversely with respect to the longest extent of the ducts 16, 17. The ribs 18, 19 connect opposing edges of the housing parts 8, 9 which delimit the respective duct 16, 17. These ribs 18, 19 ensure an intended stability in the region of the ducts 16, 17, so that the housing parts 8, 9 can be produced from plastic. FIG. 2 also shows that the housing parts 8, 9 are connected to one another by means of screws 20. The screws 20 are screwed into steel nuts 21 arranged in one of the housing parts 8. The housing part 8 has receptacles 22, formed as recesses, for the nuts 21. 

1. A gerotor fuel pump for feeding fuel from a fuel tank of a motor vehicle having a housing, having a rotor pair mounted between two housing parts, and having elongated inlet and outlet ducts arranged in the housing, characterized in that at least one of the ducts (16, 17) has at least one rib (18, 19) for strengthening the housing (10).
 2. The fuel pump as claimed in claim 1, characterized in that the at least one rib (18, 19) is arranged transversely with respect to the longest extent of the duct (16, 17) cross section, and connects opposing edges of the housing (10), which delimit the duct (16, 17), to one another.
 3. The fuel pump as claimed in claim 1 or 2, characterized in that the rib (18, 19) is produced in one piece with those regions of the housing (10) which adjoin the ducts (16, 17).
 4. The fuel pump as defined in claim 1, wherein at least one of the housing parts (8, 9) is produced from plastic.
 5. The fuel pump as defined in claim 4, wherein the housing parts (8, 9) are screwed to one another, one of the plastic housing parts (8) having receptacles (22) for metal nuts (21). 